JPS60254804A - Method and device for noise reduction of cassegrainian antenna - Google Patents

Abstract

PURPOSE:To correct the direction of a ground station, etc., to an object of transmission and reception through an antenna when the station deviates in the direction to the object, and prevent deterioration in radiation characteristics of the antenna by specifying the position of the phase center of a primary radiator. CONSTITUTION:Primary radiators 131-134 are arranged having center phases of their opening parts 13a on a focal plane X (close to a spherical surface having the center almost at a point O) obtained through main and sub reflectors 11a and 12. Both reflectors 11a and 12a move to other optional positions within the track of revolution around the point O while holding mutually geometric position relation. Consequently, if the ground station devices in the direction to the object of transmission and reception, the direction is corrected through the antenna. Further, the mutual position relation between both reflectors is never lost, so deterioration in radiation characteristics is prevented.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a method and apparatus for reducing noise in a Cassegrain antenna suitable for use in broadcasting satellites, etc., and particularly improves beam pointing to a transmission/reception target such as a ground station. 〇 [Technical Background of the Invention] Generally speaking, this type of antenna uses two reflecting mirrors (main and sub-reflecting mirrors) and one primary radiator, based on the principle of a Cassegrain telescope in the field of optics. It is configured. The function of this antenna with two reflectors can be handled in the same way as a parabolic antenna with a single reflector, so a small aperture of the -order radiator is sufficient, and the sub-reflector absorbs the radiation waves from the primary radiator. It should be large enough to receive it. In addition, since the primary radiator and transmitter/receiver can be directly connected to this antenna, there is less power transmission loss in the feeding system, and when radiating into space, the leakage power from the sub-reflector is directed toward the celestial body, so there is less noise. It has the following advantages. When beam pointing is performed in some antennas, the sub-reflector is appropriately tilted. That is, to explain this using a diagram, the beam afi emitted from the -order radiator (1) is once received by the sub-reflector (2) having a hyperboloid, and then -
The reflected beam is supplied to the main reflecting mirror (3), and is reflected back to emit a beam with the same directionality.
◎ [Problems in the Background Art] However, in an attempt to minimize the distance between the sub-reflector and the main reflector to make the antenna device more compact, a curved surface with a relatively large curvature is used as the sub-reflector. Accordingly, when attempting to take beam pointing by appropriately tilting this sub-reflector, the larger the curvature, the greater tl.In other words, the larger the aperture angle of the main reflector, the more the antenna will be affected by its optical aberration. Deterioration of radiation characteristics is observed.

In addition, as a countermeasure to this, it is possible to perform beam pointing by moving the primary radiator, but in this case, the feeding circuit (waveguide, etc.) needs to have a flexible structure, which is particularly important for multiple If it were to be used for multiple beams using multiple primary radiators, its structure would be more specific, making it extremely difficult to manufacture.

[Purpose of the invention]

Misfire F! This was done in consideration of the above points, and it is possible to correct the direction of the transmitting/receiving target such as a ground station when the direction shifts using the antenna, and at the same time prevent the deterioration of the antenna's radiation characteristics. The present invention provides a method and apparatus for reducing noise in a Cassegrain antenna.

[Summary of the invention]

In other words, using an optical rich-effect-reflection type antenna obtained by the periphery Galindo method, the phase distribution is corrected by a mirror surface correction technique that slightly deforms the main and sub-reflected bell tones, keeping the phase distribution uniform. , the main and sub-reflectors can be moved together without changing their relative positions.

[Embodiments of the invention]

The unexploded BA will be explained below with reference to one embodiment shown in Figs. 1 and 2. This is a sub-reflector device that has a surface made of a conductive material such as plastic or aluminum and has a concave hyperboloid that totally reflects the beam.The sub-reflector device consists of a sub-reflector 02a) and this sub-reflector. (12a) The main reflecting mirror device (11) is composed of a driving device (12b) that rotates t-.
11a) and a drive device (Rlb) that rotates this main reflecting mirror (11a). (131)～034
) is a large number of primary radiators that emit beams, for example, the beams emitted from this -order radiator (1'32) and (13a) are as shown by arrows Z 2 + Z 3 in FIG. The light is reflected by the sub-reflecting mirror (12a) and the main reflecting mirror (11a), and is emitted in different predetermined directions. These -order radiators (1:h) ~ (
134) The combination of the sub-reflector (12a) and the main reflector (11a) constitutes a rich-effort channel offset Cassegrain antenna. The -order radiator (13
1) to (134), as shown in Figure N2, the phase center of the aperture 03a)... is set to the focal plane (obtained by selecting the curvature of the main and sub-reflectors so that the surface is close to a spherical surface).

The drive device (12b) and Q 1 b) have respective reflecting plates (12a) and (11a) that rotate on the orbit as shown by the arrow y in FIG. 2 with the point O as the central axis. It is arranged to move and come to a position as shown by a two-dot chain line, for example. This is for each reflecting mirror (12a) and (lla)
ld, each of which moves while maintaining its geometrical positional relationship. That is, for this movement, these drive devices (1, 2b) and (1
The driving device (12b) has a configuration in which the reflecting mirrors (12a) and 01a) move in the same way as if they revolved at a predetermined angle around the 0 point while maintaining their respective relative relationships by driving the reflecting mirrors (12a) and 01a). The control method for (1l b) is as follows:
The orbit of the sub-reflector centered on the 0 point is electronically stored in advance, and one of the reflectors (12a) or (11)
When A) makes a command from the ground station or automatically makes any movement, the other reflector (11a) or (12
a) The position where a geometrical positional relationship is maintained with respect to the one reflecting mirror can be completely automatically calculated, and the driving device can be operated and automatically controlled based on this. At this time, the above-mentioned arbitrary movement must be one that corrects the deviation in the attitude of the artificial satellite.

Note that (14) U is a base supporting the above-mentioned Cassegrain antenna, and is attached to a main body of transmitting/receiving equipment (not shown) such as an artificial satellite.

The primary radiators (131) to (134) are attached to artificial satellites and transmit beam information received from one ground station.
) Any beam Z2. 'Z3 ffi output,
7. : Then, each of these beams is reflected by the sub-reflector 02.
a) and the main reflecting mirror (11&), the light is emitted in different directions. In this way, beam information can be transmitted in different directions.

Here, if a slight deviation occurs in the attitude of the artificial satellite itself, the directions of the sub-reflector and the main reflector are completely changed in order to correct it either by a command from the ground station or automatically. That is, as described above, by operating each reflecting mirror device, each reflecting mirror moves while maintaining its relative position so that the radiation beam is directed toward a transmission/reception target such as a ground station, thereby transmitting and receiving data.

On the other hand, if the embodiment shown in FIG. 3 is explained by assigning the same reference numerals to the same parts as in FIGS. 1 and 2,
As shown in the figure, the sub-reflector (12a) and the main reflector (
11a) are arranged in a predetermined geometric positional relationship, and these are respectively c) 1), +addition and t22)
, f23, and is rotatably supported by a two-axis drive device Hibiki. The two-axis drive device Q31rl is connected to a U-shaped arm and a first control motor (c) so as to be able to rotate about its central axis. The arm (2
A second control motor ＼,＠ that rotates in a direction perpendicular to the rotation direction of this arm is attached to both ends of 4), and the sub-reflector (not shown) is attached to this shaft (not shown). 12a) and the spider (2i+, (2i+) of the main reflector (11a)
and 12a, (0 to which 2a is attached) The line connecting this second motor ■, (4) corresponds to the 0 point in the embodiment of FIG. 2. (13□) to (134) '
are primary radiators, and as in the case of the embodiment shown in FIG. 2, the phase centers of these apertures α3a) are the main and sub-reflecting mirrors (1ia).

(12a)'i is arranged so as to be located on a substantially spherical focal plane (not shown) obtained by interposing.

The primary radiators (131) to (134) are attached to artificial satellites and transmit beam information received from one ground station.
), J: If a plurality of arbitrary beams are output, as in the above embodiment, each of the beams is radiated in different directions via the sub-reflector (12a) and the main reflector αla). It becomes like this. In this way, beam information can be transmitted in different directions.

If there is a slight deviation in the attitude of the satellite itself, the direction of the sub-reflector and main reflector is changed by a command from the ground station or automatically to correct the deviation.
In other words, in this control method, the second control motor ■, a6)'e is operated by command from the ground station or by self-study, and the Eri sub-reflector (12a), (ll
a) is operated so that the radiation beam is directed toward a transmission/reception target such as a ground station.

〔Effect of the invention〕

According to the present invention, in the antenna in which the beam emitted from the primary radiator is transmitted and received via the sub-reflector and the main reflector as described above, the phase center of the aperture of the -order radiator is , each of which is arranged in the shape of a spherical surface, and the main and sub-reflecting mirrors are arranged arbitrarily within the orbit of revolution around the center point of the spherical surface while maintaining a mutual geometrical positional relationship. This method allows beam pointing to a transmitter/receiver target such as a ground station, so that the beam emitted from the -order radiator can When beam pointing cannot be achieved due to the directionality of the beam, the directionality of the transmitting/receiving target is fully controlled while maintaining the predetermined positional relationship between the sub-reflector and the main reflector. In order to appropriately control the direction of the beam emitted from the second radiator in a predetermined direction and transmitted in a predetermined direction via the sub-reflector and the main reflector, internal reflection This makes it possible to eliminate the deterioration in the quality of radiation characteristics due to the occurrence of aberrations that may occur when the relative positions of the mirrors are distorted.

Furthermore, in the case of the embodiment shown in FIG. 3, the phase center of each of the apertures of the plurality of primary radiators is close to a spherical surface obtained by passing through the main and sub-reflecting mirrors. Since the satellite is positioned on the focal plane However, since there is a wide range of placement of multiple primary radiators, any one of the primary radiators can be used to function, making it possible to widen the range of beam pointing for transmission/reception targets such as ground stations. Therefore, it is possible to widen the tolerance range for the attitude deviation of the artificial satellite itself.

It should be noted that the present invention is not limited to the above-described embodiments, and for -order radiators, as shown by the dotted lines in FIGS. In other words, they are arranged vertically and horizontally, and a drive device or control motor is operated to move the internal reflector in three dimensions, and the beam pointing area for transmitting and receiving targets such as ground and upper stations is To make it wider ((can be done.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing the present invention, Fig. 2 is a side view of Fig. 1, Fig. 3 is a perspective view showing another embodiment of the invention, and Fig. 4 is a perspective view showing a conventional example. 〇θυ・・・Reflector device, (
lla)...main reflecting mirror, (llb). (12b) ``'Drive device, (12a) - Sub-reflector, (131) to α34)... - Secondary radiator, ■... Base, (21) 122)... Spider, (Ha )・・
・Two-axis drive device, (Foundation)...U-shaped arm, (C)・
・・First control motor, Ka)・・Second control motor Agent Patent attorney Noriyuki Chika (and 1 other person)

Claims (3)

[Claims] (1) In an antenna in which the beam emitted from the -order radiator is transmitted and received via a sub-reflector and a main reflector, the phase center of the aperture of the -order radiator connects the main and sub-reflectors. The main and sub-reflecting mirrors are arranged so as to be located on a nearly spherical focal plane obtained by using 1. A method for reducing noise in a Cassegrain antenna, characterized in that the antenna can be moved to any other position within a ground station and performs beam pointing to a transmitting/receiving target such as a ground station. (2) In an antenna in which the beam emitted from the -order radiator is transmitted and received via a sub-reflector and a main reflector, the phase center of the aperture of the -order radiator is A revolving trajectory centered on the center point of the spherical surface while maintaining the mutual geometrical positional relationship of the main and sub-reflecting mirrors, which are arranged so as to be located on a nearly spherical focal plane obtained by interposing a mirror. A device for reducing the noise of a Cassegrain antenna, characterized in that a two-axis drive device is provided so that it can be moved to any other position within the Cassegrain antenna. (3) A plurality of the -order radiators are arranged on a nearly spherical focal plane whose phase center of the aperture is obtained through the main and sub-reflecting mirrors. A noise reduction device for a Cassegrain antenna according to Scope 2.